These are the days of hot sun and mortgage refinance frenzy. Somehow, they've both combined in my mind to make me ponder the economics of a solar water heater.

Because the sun's been beating down on our garden hose, the initial flush of water can be very hot. The warm spray reminded me of the times on camping trips when we'd bring along a portable solar shower -- essentially a black plastic bag with a tube and shower nozzle -- for bathing. While not an endless supply (perhaps 10 gallons), it was a very enjoyable luxury. Of course, it assumes that there's plenty of sunshine, but if so -- voila -- a warm and sudsy campsite clean-up is possible.

For some reason, with that thought in mind, I began wondering about adopting a solar water heating system for our Colorado house. Because I'm pretty sure coiling a few lengths of garden hose on the roof won't cut it, I began wondering if an installation made sense.

It was then that I checked out the Energy Savers site on the economics of solar water heaters. Not surprisingly, solar water heating systems usually cost more to purchase and install than conventional water heating systems. The good news is that a solar water heater can usually save you money over time, depending on variables such as the amount of hot water a consumer uses and the cost of the conventional fuels. On average, I could cut our water heating bills 50 to 80 percent.

Even better, the economics make sense for a refinancing. In the Energy Savers example, the price of a solar water heater in a new 30-year mortgage usually amounts to between $13 and $20 per month. But a federal income tax deduction for mortgage interest attributable to the solar system reduces that by about $3–$5 per month. So if fuel savings are more than $15 per month, the solar investment would be profitable immediately.

Armed with that knowledge, I plan to do some more shopping. But as it stands, I like the idea of adding such a system to the mix. That seems to make more sense than leaving the hose out in the sun.